Joined: 14-Feb-07 10:05
The principle reason to merge layers is to trim/simplify the history of incremental backups in your archive. This frees up the space occupied by those earlier layers, which becomes available for new captures. So instead of growing forever, your archive becomes a conveyer belt: capturing new changes while letting ancient changes fall of the other end.
If you have sufficient disk space, you don't care how big your archive gets, and you don't mind wading through hundreds of layers to find an old version of something, then you don't have to merge layers.
The only difference between a "merge" and a "rolling merge" is that the rolling merge automatically selects groups of layers to merge based on a rolling calendar. Other than that, there's no difference. Or said another way, a simple merge will merge a range of layers based on a formula that you give it, while a rolling merge picks sets of layers to merge based on calendar intervals you choose.
If you want the traditional "rolling backups" provided by conventional backup solutions, the rolling merge automates that for you. But if you want absolute control on what gets merged and when, then the simple merge action (or doing it manually in the QRecall app, or rolling your own logic using the command-line tool) is at your disposal.
Finally, if you have a merge action, see if it has conditions. For example, if you tell the capture assist that you want to keep as much history as possible, it will create a merge action that merges the oldest layers in the archive, but only if the free space on the disk is below a certain threshold. The end result is a merge action that never runs until the disk starts to fill up. It then runs every day until the size of the archive is reduced enough to to stop it running again.
I hope that helps!